1. Field of the Invention
The present invention is generally related to a battery monitoring system and, more particularly, to a system that continually monitors the voltage across the terminals of a storage battery of a marine vessel and, in response to a low voltage potential across the battery, automatically selects electrical loads that are to be shed in order to protect the battery from depletion.
2. Description of the Prior Art
In marine vessel electrical systems, it is very important to protect the electrical storage battery from inadvertent and unexpected depletion. Unlike ground-based vehicles, such as automobiles, tractors, trucks, and motorcycles, a marine vessel with a depleted battery and an inability to start the engine of the marine vessel can be very distant from its home port or any other location where emergency assistance can easily be obtained. Therefore, it is well known to those skilled in the art that the charging and maintenance of an electrical charge across an electrical storage battery of a marine vessel is very important. It is also very important that the use of the battery to provide power for certain electrical loads on the marine vessel be monitored to make sure that the battery isn""t inadvertently depleted by running excessive loads without providing an effective recharging of the battery.
U.S. Pat. No. 6,342,775, which issued to Sleder on Jan. 29, 2002, discloses an automatic battery switching circuit for a marine propulsion system. The circuit provides a mechanism by which a plurality of electrical storage batteries can be alternatively connected in parallel or series based on the position of a manually controlled joystick of a marine positioning and maneuvering system. When the joystick is in a neutral position in which no docking motion is demanded by the marine vessel operator, the storage batteries are connected in parallel so that they can benefit from charging by an alternator or generator associated with an internal combustion engine. If the joystick is moved out of its neutral position, the batteries are immediately connected in series to provide power to a plurality of electrical motors that are used to drive a plurality of impellers of the docking system.
U.S. Pat. No. 5,963,013, which issued to Watson et al on Oct. 5, 1999, describes a storage battery charging apparatus and methods. The apparatus and method for charging a battery in a transported apparatus from the electrical system of a transporting vehicle is described. In one aspect of the invention, there is provided a circuit means for determining when a battery has been sufficiently recharged, adapted to be respectively coupled to both the battery of the transported apparatus and the electrical system of the transporting vehicle. The circuit means may include means for determining the status of the battery being charged such as a meter, an array of lights, or an array of light emitting diodes, the number and sequence of illumination being indicative of the extend to which the battery has been recharged.
U.S. Pat. No. 5,896,022, which issued to Jacobs on Apr. 20, 1999, describes a battery charge managing system. A modification kit for the addition of an auxiliary battery charge management system for a marine or land vehicle having a starting battery and an auxiliary battery is described. The kit includes a single pole breaker, a normally-on relay, and a two-way toggle switch. The single pole breaker is inserted in a circuit of the auxiliary battery system and the normally-on relay and the toggle switch are inserted in the starting battery circuit of the vehicle to provide a dual mode charging system adapted to manual and automatic power regeneration of the starting battery and the auxiliary battery system.
U.S. Pat. No. 5,448,152, which issued to Albright on Sep. 5, 1995, describes a battery management system. The system maintains a charge on at least one auxiliary battery by switching the auxiliary battery automatically into parallel with the main battery charging circuit or with the auxiliary load. The system uses the AC component of the charging signal of a vehicle or boat charging system to trigger switching circuits coupled to operate relays or similar switching means which couple the auxiliary battery to the main charging circuit. When no charging signal is present, such as when the vehicle or boat engine is turned off, the auxiliary battery is switched automatically out of the charging system and is charged and in condition for use.
U.S. Pat. No. 5,315,287, which issued to Sol on May 24, 1994, describes an energy monitoring system for recreational vehicles and marine vessels. The invention continuously monitors the current drawn from the on board battery system of a recreational vehicle marine vessel. The device calculates and displays the energy remaining as a portion of the total capacity by accumulating over time the net energy drawn out of the battery. The device accurately accounts for the known effect of effectively lower battery capacities at higher current draws, and also allows the user to reinitialize the battery system capacity to reflect either degradation of the battery capacity with time or upgrades to the battery system.
U.S. Pat. No. 4,468,606, which issued to Quintal on Aug. 28, 1984, describes a system for charging the battery and operating the electrical accessories of a sailboat. The system comprises an alternator having a stator winding adapted for connection to the battery through suitable current rectifiers and a rotor field winding coupled to the auxiliary propeller shaft of the boat. Circuit means for controlling the energization of the field winding of the alternator from the output voltage of the stator winding, so as to permit the alternator to provide adequate current to charge the battery and operate the electrical accessories of the sailboat, and a voltage regulator adapted for connection to the field winding of the alternator for controlling the output voltage of the stator winding when such output voltage reaches a predetermined value.
U.S. Pat. No. 5,126,650, which issued to Iwatani on Jun. 30, 1992, describes an indication device for a vehicle charging and generating system. The device is capable of informing the operator of the relation between the amount of power generation available and the amount of electrical load applied, thereby enabling the operator to turn off unnecessary electrical loads to prevent the overdischarging of a battery. The indication device includes an AC generator having a field coil and driven by a vehicle engine, and a storage battery connected to an electric load and to the generator. A voltage regulator detects the output voltage of the generator or the voltage of the battery and has a power transistor electrically connected in series with the field coil of the generator to regulate the output voltage of the generator at a prescribed level. A converter operates to convert the rate of electrical conduction of the power transistor into a corresponding voltage level, and an indication meter is connected to the converter to display the utilized percentage of power generating capacity of the generator.
U.S. Pat. No. 5,352,929, which issued to Kohl et al on Oct. 4, 1994, describes an apparatus and method for regulating a generator of an internal combustion. The system has a starter device including a charge control signaling device, an excitation coil for the generator and a voltage regulator controlling an excitation current in the excitation coil and an excitation current limiting device for limiting the excitation current during a predetermined starting phase connected to the voltage regulator. The excitation current limiting device detects whether the engine is in a starting phase. If the engine is in a starting phase, the excitation current limiting device reduces the excitation current so that a voltage is produced at a generator terminal which permits no load current and simultaneously guarantees that the charge control signaling device is shut off. After ending of the starting phase the excitation current limiting device is shut off and the excitation current is increased to its standard value which results in a generator output voltage which is above the power supply voltage that charges the battery.
U.S. Pat. No. 6,273,771, which issued to Buckley et al on Aug. 14, 2001, discloses a control system for a marine vessel. The control system incorporates a marine propulsion system that can be attached to a marine vessel and connected in signal communication with a serial communication bus and a controller. A plurality of input devices and output devices are also connected in signal communication with the communication bus and a bus access manager, such as a CAN Kingdom network, is connected in signal communication with the controller to regulate the incorporation of additional devices to the plurality of devices in signal communication with the bus whereby the controller is connected in signal communication with each of the plurality of devices on the communication bus. The input and output devices can each transmit messages to the serial communication bus for receipt by other devices.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
As is well recognized by those skilled in the art, the monitoring and protection of a storage battery""s voltage potential to start the marine engine of a marine vessel is highly important in order to assure that the marine vessel is capable of returning to its home port or to a shore based location where maintenance can be performed on the marine vessel if a component or system malfunctions.
A method for controlling the electrical system of a marine vessel, made in accordance with the preferred embodiment of the present invention, comprises the steps of measuring the voltage potential of an electric storage battery of the marine vessel. It also comprises the step of comparing the voltage potential to a threshold voltage potential. The preferred embodiment of the present invention then disconnects one or more of a plurality of electrical power consuming devices when the voltage potential of the storage battery is less than the threshold voltage magnitude.
In certain embodiments of the present invention, the method further comprises of measuring the operating speed of the engine of the marine vessel, comparing the operating speed of the engine to a threshold speed magnitude, and performing the disconnecting step only when the operating speed of the engine is less than the threshold speed magnitude.
In a particularly preferred embodiment of the present invention, the method further comprises the steps of communicating to an operator of the marine vessel that the voltage potential is less than the threshold voltage magnitude and then performing the disconnecting step unless the operator of the marine vessel manually overrides the disconnecting step. The present invention can further comprise the step of waiting for at least one minute following the communicating step for a response from the operator of the marine vessel before performing the disconnecting step.
In a particularly preferred embodiment of the present invention, it further comprises the step of classifying each one of the plurality of electrical power consuming devices according to its priority of criticality, wherein the priority of criticality is determinative of the order in which each of the plurality of electrical power consuming devices is disconnected during the disconnecting step. The classifying step can comprise the steps of grouping the electrical power consuming devices into a level of priority of criticality which is selected from the group consisting of critical and non-critical. The classifying step is performed in accordance with manually received instructions from the operator of the marine vessel in a preferred embodiment of the present invention.
After performing the disconnecting step, one embodiment of the present invention further comprises the step of measuring the voltage potential of the battery again in order to determine the efficacy of the disconnecting step.
A preferred embodiment of the present invention further comprises the steps of measuring a current consumption of at least one of the plurality of electrical power consuming devices and comparing the current consumption of that measured device to a threshold current magnitude. That embodiment of the present invention further comprises the step of disconnecting the electrical power consuming device when the current consumption of that device is greater than the threshold current magnitude.
In a preferred embodiment of the present invention, the measuring and comparing steps are repeated at a frequency of at least once per second.